1. Field of the Invention
The present invention generally relates to theatrical and architectural luminaires and, more specifically, to a white LED luminaire with imaging capability including changing colors, shapes and projecting static and dynamic images.
2. Description of the Prior Art
In the entertainment lighting industry, numerous luminaires are known for creating various lighting effects with both static and movable and controllable spot lights.
For example such luminaires such as ellipsoidal reflector spotlights are made available by Altman Lighting, Inc. of Yonkers, N.Y. as fixed focus luminaires under Model Nos. S6C-5, S6C-10, S6C-20, S6C-30, S6C-40 and S6C-50. Similar luminaires are also available as zoom ellipsoidal spotlights, made available by Altman Lighting, Inc. under its trademark “Shakespeare” under Model Nos. S6C-1535Z and S6C-3055Z. The aforementioned luminaires are typically configured with 120 volt lamps that typically vary from 575-1000 watts. The luminaires include an ellipsoidal reflector that projects light through a condenser lens, the resulting beam passing through a shutter assembly and a gobo iris plate slot, these being traditionally used to mechanically dim or blackout the light beam projected downstream and to impart to the beam a desired design within a spotlight by projecting the illuminated representation of a design. The beam is then directed through an objective projection optical lens system for focusing the beam and/or projected design. These fixtures also typically include a gel frame holder for securing color gel sheets or color filters to modify the color of the projected beam.
While ellipsoidal projectors are staples in the entertainment and theatrical lighting industries, they generate large quantities of heat. Also, lamps typically used are rated between 5,000-12,000 hours before they have to be replaced. Normally, the higher the voltages of the bulbs, the shorter the lifespan. Therefore, these lamps need to be changed periodically and this can be problematic as these luminaires are frequently secured on tresses or beams high above the ground in theaters, stadiums and the like. Also, while such luminaires have provided many of the desired functions, they have also lacked some flexibility in use since the shutter assemblies, the gobo rotators and the insertion or exchange of gel plates must frequently be adjusted manually. Because these luminaires are frequently inaccessible, it has sometimes been necessary to use a number of luminaires, each set for different beam property, such as color pattern, etc. and the appropriate luminaires energized to obtain the desired effect(s). Therefore, once these luminaires are set up for a given type of beam, it is usually fixed in that condition to generate only that type of beam.
In order to reduce the heat generated by conventional luminaires and to increase the lifespan of the light sources, more and more use has been made of light emitting diodes (LEDs). While LEDs consume much less energy and have longer lifespans, LEDs are only now beginning to generate the light intensities that make them useful in commercial luminaires and light or image projectors used for stage lighting and other such applications. Many of the known LED luminaires employ clusters of red, blue and green (RCB) primary color LEDs. By controlling each of the LEDs the luminaires can project different color beams. In theory, energizing all three primary colors red, green, blue LEDs create a white light beam. However, in practice, such luminaires have not been totally acceptable. One of the primary functions or requirements of luminaires is to project a beam of pure or white light. However, because differently colored LEDs emit different hue, saturation and brightness or intensify of light for given currents driven through the LEDs, it is difficult to match the color outputs in the proper proportions to provide a purely white beam. The intensity of a spectral color may alter its perception considerably; for example, a lower intensity orange-yellow may appear to be a brown, while a low intensity yellow-green may appear as olive-green. In fact, in practice, no mixture of colors can produce a fully pure color perceived as completely identical to a spectral color. Accordingly, if the “primary” colors are not pure themselves, any combinations of the colors reproduced are never perfectly saturated colors, and so spectral colors cannot be matched exactly. Also, different color LEDs generate colors that are slightly off from each other, so that two green LEDs, for example, do not always emit the identical colors and, when mixed with other “primary” colors will not generate pure white light. Thus, while LED luminaires have been proposed and they do provide cooler light with the ability to modify color, they have been less than satisfactory in projecting a powerful white light beam.
Also known are LCDs projectors that utilize a light source for projecting a light beam onto an LCD panel. By controlling the signals to the panel image information can be imparted to the beam that is generated by the panel and a modified beam can be projected using conventional optical system. Thus, for example, in U.S. Pat. No. 6,409,350 an LCD projector is disclosed that includes an image data source producing image data. A light source provides light projected onto an LCD panel which modifies the light emitted from the light source in accordance with the image data. A projector lens projects the image from the LCD panel to an enlarged screen. The LCD acts as an image forming member. The light source is disclosed as being a luminescent lamp, such a mercury lamp. The image data inputted into the LCD screen is processed by a color correcting circuit to control or modify the three primary RGB colors output BY the LCD panel. This is another approach for obtaining a white light beam. However, the use of such color correction circuitry by use of look up tables and the like increases the cost of the unit and provides a desired output only when the correction circuitry functions properly.
In U.S. Pat. No. 6,765,544 an image projection apparatus is disclosed that includes a viewing surface dependent image correction. The apparatus includes a deflector to deflect a light beam from a video projector in a plurality of directions. An image processing circuit is used to process image information to modify the image information and provide a desired light output. The apparatus generates a beam by means of a lamp and an ellipsoidal reflector, the lamp being situated at the focal point of the reflector. Although the patent does not specifically discuss the nature of the lamp used, it is illustrated as being an incandescent or gas discharge type lamp. An image generating engine is disclosed that alters the shape of the light beam to generate an image in a light beam using a DLP device of the type made available from Texas Instruments, Inc. and typically comprises a plurality of digitally controllable micro mirrors.
U.S. Pat. No. 6,979,960 discloses a circuit for driving a light source. The patent discloses a light source capable of lengthening the lifespan of the light source by using a circuit that controls the device to drive the light source, which is composed of a discharge tube. By switching the light source to a plurality of lighting modes and controlling the power applied to the light source, the light source cannot break within its safety limits. The patent discloses the use of a high pressure mercury lamp as the light source. However, it is also suggested that the metal lamp or halogen lamp can also be used.
An image projector is disclosed in U.S. Pat. No. 7,111,944. The patent discusses a use of a high intensity discharge lamp as a light source for displaying an image brightly. The projector uses a discharge lamp and a micro mirror device (DLP). The micro mirror device serves as an image generator by controlling each micro mirror corresponding to image data to reflection direction of a light beam admitted from discharge lamp.
U.S. Pat. No. 7,232,236 discloses a floor marking apparatus for creating a pattern on a floor including a graphic pattern and a color pattern.
Thus, prior art ellipsoidal reflector spot lights that have used of LEDs and those that have also incorporated image engines in the form of LCD panels have had shortcomings and have not been suitable for many applications. Most gas discharged lamps typically used in ellipsoidal luminaires or spotlights employ noble gases such as argon krypton xenon, or mixtures of these gases. Most of these lamps are also filled with additional substances such as mercury, sodium and/or metal halides. However, each gas, depending on its wavelengths, translates into different color spectrums of the lamp. The International Commission on Illumination (CIE) has, therefore, introduced a color rendering index. Some gas discharged lamps have relatively low CRI, which means colors they illuminate are substantially different than they appear under sunlight or other high-illumination. Helium gas lamps typically emit a white to orange and, on some conditions, may be grey, blue or green-blue. Neon gas generally emits a red-orange color. Argon emits a violet to pale lavender blue while krypton emits off-white to green. Under high peak current krypton emits a bright blue-white. Xenon emits a grey or blue-grey dim light and at high peak currents a very bright green-blue color light. Nitrogen has color properties similar to argon but somewhat more pink and at high peak currents a bright blue-white. Oxygen emits a violet to lavender, while hydrogen emits a lavender at low currents while emitting a pink to magenta over 10,000,000 mA. Mercury vapor lamps frequently emit a light blue, intense ultraviolet light while sodium vapor (at lower pressure) emit a bright orange-yellow color light. As evident, therefore, not only do RGB clusters of LEDs fail to reliably generate pure white light but also most gas discharge lamps fail to provide such white light.